The biographical pages of MPs on the online encylopedia Wikipedia have been
altered to remove details of past humiliations, it can be revealed.

Getting caught up in a scandal or being publicly embarrassed is an occupational hazard for politicians.

Now there are suggestions that some have tried to rewrite history by deleting mentions of their career low-points from Wikipedia, the user-edited online encyclopedia.

An investigation has uncovered dozens of cases where MPs' biographical pages on Wikipedia were altered to remove details of past humiliations which had been added by members of the public.

Embarrassments which have been deleted include an MP who employed a male escort, an MP who lost his front bench job in a row over racist language, and a female MP whose ex-husband was arrested and deported.

On every occasion, the change was made either by someone working within the parliamentary estate or by a user who appeared to have links to the MP.

Clive Betts, the Labour MP for Sheffield South East, had his Wikipedia entry edited to remove references to his employment of a Brazilian male escort with whom he was alleged to have had a relationship.

A Wikipedia user with the name "Jamesthomas101" deleted the information. James Thomas is Mr Betts's partner, and also works as his parliamentary assistant.

Another user deleted references to allegations that Mr Betts received tickets, hospitality and accommodation from McDonald's, the hamburger chain, at the Euro 2004 football tournament and the 2006 World Cup, and his later tabling of a Commons motion in support of the company's campaign to end the use of the term "McJob".

In March this year the page of Tony Baldry, a former Conservative minister, was changed three times by a user calling himself "Tonybaldry".

On March 24 information was removed about alleged lobbying by Mr Baldry on behalf of Milestone Trading, a diamond mining company from which a company in which he was a one-third shareholder had reportedly received payments.

The same user also deleted the information that Mr Baldry, the MP for Banbury, had recommended for a CBE a lawyer from whom he had borrowed £5,000.

The MP was ordered to apologise to the House of Commons as a result of the incident.

Three days after the first edit, after the references were reinserted by another user, "Tonybaldry" again deleted them.

At that point, Wikipedia's monitors sent a warning to "Tonybaldry" asking him to refrain from editing the entry if, "as your user name suggests, you are somehow connected to Tony Baldry". "Tonybaldry" has not edited a page since.

Mr Baldry said the changes had been made at his request by one of his parliamentary researchers.

He said: "The Wikipedia rules are self-serving rules of engagement. It's impracticable to sue Wikipedia so the only thing you can do is to hope that the entries are accurate.

"It seems wholly unreasonable that people can go onto the website and simply write stuff that is inaccurate or libellous about public figures. I'm not sure who one can rely on unless oneself to correct the information.

"I was simply trying to ensure that it wasn't libellous and that it wasn't seriously misleading."

In July 2009 Patrick Mercer's Wikipedia entry was changed 31 times by a user with a parliamentary Internet Protocol (IP) address, suggesting that the changes were made by someone within the Palace of Westminster.

Two years earlier, Mr Mercer had resigned from the Conservative front bench after he said in an interview that being subject to racist abuse, such as the term "black *******", was a normal part of Army life for ethnic minority soldiers.

Among the changes made to his Wikipedia entry was the deletion of a reference to his resignation.

The Wikipedia entry for Harriet Harman, the acting Labour leader, was changed in July 2008 by a parliamentary user to delete a reference to a protest on the roof of her London house by Fathers 4 Justice campaigners which had taken place the previous month.

The section has since been reinserted, although it has been substantially rewritten.

The entry for John Bercow, the Speaker, was changed from inside parliament in October 2005 to remove information that he stood for election to the executive of the Monday Club, a Tory grouping, in 1981 on a ticket of opposing immigration and calling for assisted repatriation.

The user who deleted the details added instead that Mr Bercow and his wife were "now the proud parents of Oliver born in December 2003. They are expecting their second child in November 2005."

A parliamentary computer was also used in March 2007 to delete details of a libel case brought by Shahid Malik, the former Labour minister and Dewsbury MP, against a local newspaper.

In another case the entry for Caroline Flint, the Labour MP and former Cabinet minister, was changed twice from a parliamentary computer. References to Saief Zammel, her first husband, were removed.

The couple divorced in 1990 after Mr Zammel was arrested on charges of violent disorder and was subsequently deported. Her page currently refers to Zammel, but not to his arrest or deportation.

In January last year the entry for Nigel Waterson, a former Tory junior minister who lost his seat in this month's election, was edited from parliament to delete a reference to reports that he had been arrested for allegedly assaulting his two teenage children, before being released without charge. It was subsequently reinserted.

In March last year a user based in parliament deleted details of an alleged fight between Philip Davies, Conservative MP for Shipley, and Stephen Pound, Labour MP for Ealing North, from Mr Davies's entry.

In February 2009 user "Curtiskeeble" edited the entry of Sally Keeble, the former Labour MP for Northampton North, to remove a mention that she was selected from an all-woman shortlist.

Curtis is her middle name, and also the name of her father.

Matthew Elliott, the chief executive of the TaxPayers' Alliance, said: "It is clearly somewhat dodgy for people to use Parliamentary resources to delete all mention of embarrassing incidents from Wikipedia.

"With the massive deficit and the crisis over expenses, you would have hoped politicians had better things to do than mess around on the internet."

There are no rules preventing staff at the Houses of Parliament from changing Wikipedia entries. The parliamentary IT policy warns users not to create material which could be "threatening, slanderous, abusive, indecent, obscene, racist, illegal or offensive".

Wikipedia's own rules of conduct discourage editing by individuals with a "conflict of interest" – which would include the MPs themselves, their staff and family members.